A wireless communication system is elaborated to prevent multiple wireless communication devices from transmitting concurrently and thus prevent cross-talk by means of a communication procedure such as CSMA/CA (carrier sense multiple access/collision avoidance). With the above communication procedure, multiple wireless communication devices shill the time of using a communication channel in a time sharing manner to prevent cross-talk.
Furthermore, multiple communication channels consisting of slightly shifted radio wave frequency bands are prepared, for example, as follows, and multiple wireless communication devices use the communication channels of the frequency bands, respectively, to prevent cross-talk.
(Exemplary 2.4 GHz band channels)
Channel 1: 2412 MHz;
Channel 2: 2417 MHz;
Channel 3: 2422 MHz;
Channel 4: 2427 MHz;
Channel 5: 2432 MHz;
Channel 6: 2437 MHz;
(snip)
Channel 13: 2472 MHz.
With the above communication procedure, if a newly activated wireless communication device selects a less frequently used communication channel, the device can use the communication channel for a prolonged time and thus conduct efficient communication.
For selecting a less frequently used communication channel, the activated communication device measures the electric field intensity of multiple available communication channels and selects an idle communication channel before starting any communication.
For example, a data communication device measuring the electric field intensity of multiple communication channels available for data communication repeatedly multiple times, comparing the electric field intensity measurement results with a threshold (“the electric field intensity threshold,” hereafter), and selecting the communication channel with the highest number of times of the measurement results being less than the electric field intensity threshold as the communication channel for use is disclosed (for example, see Patent Literature 1).
The above wireless communication device can prevent cross-talk with other wireless communication systems as much as possible even in a communication environment that includes a mixture of various communication devices.